Re: [Freedreno] [PATCH v3 06/10] drm/msm/dsi: Migrate to drm_dsc_compute_rc_parameters()

[Abhinav Kumar]

On 10/17/2022 6:37 AM, Caleb Connolly wrote:
> On 17/10/2022 09:59, Marijn Suijten wrote:
> > On 2022-10-13 09:02:44, Abhinav Kumar wrote:
> > > On 10/13/2022 2:36 AM, Marijn Suijten wrote:
> > > > On 2022-10-12 16:03:06, Abhinav Kumar wrote:
> > > > > [..]
> > > > > But I would like to hold back this change till Vinod clarifies because
> > > > > Vinod had mentioned that with drm_dsc_compute_rc_parameters() he was
> > > > > seeing a mismatch in the computation of two values.
> > > > >
> > > > > slice_bpg_offset and the final_offset.
> > > >
> > > > Unsurprisingly so because final_offset, and slice_bpg_offset through
> > > > initial_offset depend directly on bits_per_pixel.  The main takeaway of
> > > > this series is that Vinod was interpreting this field as integer instead
> > > > of containing 4 fractional bits.  If he updates his the panel driver [1]
> > > > to set bits_per_pixel = 8 << 4 instead of just 8 to account for this,
> > > > the values should check out once again.
> > > >
> > > > [1]: https://git.linaro.org/people/vinod.koul/kernel.git/commit/?h=topic/pixel3_5.18-rc1&id=1d7d98ad564f1ec69e7525e07418918d90f247a1
> > > >
> > > > Once Vinod (or someone else in the posession of a Pixel 3) confirms
> > > > this, I can respin this series and more explicitly explain why the FIXME
> > > > was put in place, instead of being resolved outright?
> > > >
> > > > - Marijn
> > >
> > > Makes perfect sense to me.
> > >
> > > Will just wait for Vinod's tested-by.
> >
> > Unfortunately Vinod doesn't have access to this device anymore, but
> > Caleb recently sent the support series including display driver for
> > Pixel 3 and is picking up the testing.  User "Newbyte" from #linux-msm
> > promised to test on the LG G7 to have even more input samples.
>
> Hi,
>
> I'm hoping to pick the Pixel 3 stuff back up at some point, but right now there
> seem to be quite a few issues outside of DSC which make testing it a bit of a pain.
>
> I gave Marijn's series [1] a go but wasn't able to get anything usable out of the
> panel, however I doubt this is a DSC issue as I've always needed some hacks to
> get the panel working - I've never had any success with it without skipping both
> the initial panel reset and sending the PPS payload.
>
> I think if Marijn has managed to initialise a panel properly then the lack of
> Pixel 3 for validation shouldn't be a blocker to merge these fixes.
>
> [1]:
> https://lore.kernel.org/linux-arm-msm/20221009184824.457416-1-marijn.suijten@xxxxxxxxxxxxxx/
>
> > - Marijn

Alright, the onus is then on Vinod/ users of pixel3 to report/debug 
whatever issues arise out of this computation.

Patch itself LGTM, hence

Reviewed-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>

> --
> Kind Regards,
> Caleb